Beersmith raises ibus with longer boil

I have a recipe in beersmith at 36 ibus with everything being added at 60 mins. I will be doing a 120 min boil as it's quite a large grain schedule so I need a lot more spathe water. When I change the time from 60 to 120 min boil but keep the hops at 60 mins the ibus go up. Why would this be?

Did you account for the water loss with the extra half hour of boil?

Just speculating, but could it be because of boil off? You will have less wort after boiling for 60 minutes so the ratio of hops to wort would increase

It automatically adjusts the water needed as I have my profile setup with the appropriate boil off rates. I will double check it but I would think it should boil off double of what it would with a 60 min boil

Could the longer boil time have an effect on the utilization of the hops? Regardless of when you add hops, I imagine there are chemical reactions happening within the wort itself for the additional 60 mins of boiling before you add the hops. There may be some coefficient at play.

http://www.realbeer.com/hops/research.html They talk about boil time factors in this, but I have only skimmed it and am not sure if maybe that plays in perhaps, or if its only after hops have been added...

now I am more confused, as I just read in "how to brew" that as the gravity of a wort increases the less AA are able to isomerize...So in theory, shouldn't the ibu's of your recipe have gone down if you left the additions the same?

"It is the gravity of the boil (1.080) that is used in figuring the Utilization. As you will see in the next section, hop utilization decreases with increasing wort gravity. The higher concentration of sugars makes it more difficult for the isomerized alpha acids to dissolve. I use the initial boil gravity in my utilization calculation; others have suggested that the average boil gravity should be used. (The average being a function of how much volume will be boiled away during the boiling time.) This gets rather complicated with multiple additions, so I just use the initial boil gravity to be conservative. The difference is small—overestimating the total bitterness by 1-3 IBUs."

In using beersmith if you only change your time of boil it shouldnt change the IBU if you add it at 60 mins.

My question is why do a 120 min boil? You brewing a dopplebock? By boiling the beer this long you will change the character of the beer do to maillard reaction or caramelization of the wort.

There is a slight increase in hop oil utilization with the increase in boiling time from 60 minutes to 90 minutes. The change is very small (only a couple of a percent).

I am making a robust porter and will be doing 2 sparges to increase efficiency.

brent77 said:

Could the longer boil time have an effect on the utilization of the hops? Regardless of when you add hops, I imagine there are chemical reactions happening within the wort itself for the additional 60 mins of boiling before you add the hops. There may be some coefficient at play.

http://www.realbeer.com/hops/research.html They talk about boil time factors in this, but I have only skimmed it and am not sure if maybe that plays in perhaps, or if its only after hops have been added...

Click to expand...

This may be it, I am seeing right now if there is anything weird going on in BS with the water volumes as that of course would definitely have an impact.

Yeah I have no clue, everything goes up exactly double when I double the time, but the more I increase the boil time, the more the IBUs go up.

It appears until you add grain the IBU's stay the same with the boil time moving, but right when you add grain the IBU's fluctuate with the boil time.

anico4704 said:

I am making a robust porter and will be doing 2 sparges to increase efficiency.

Click to expand...

Interested in this process, are you fly or batch sparging? I would like a little more details of you process. Im trying to wrap my head around this.

eluterio said:

Interested in this process, are you fly or batch sparging? I would like a little more details of you process. Im trying to wrap my head around this.

Click to expand...

Batch sparging, but this I believe applies to both fly and batch. I have read that for higher gravity beers since you have to mash with so much water there is not enough water to fully rinse the grain in the sparge, thus resulting in a much lower efficiency(10-15% lower at least). I am going to do 2 sparges or one giant sparge thus increasing my preboil volume and having to boil longer to get to my OG, hopefully keeping my normal efficiency of 74%. This is a well documented process for large grain bills if you search around google there are far more details than I can provide.

Boil without hops the first hour - if I follow - add your hops at 60 minutes remaining.

The first hour just reduces your volume and doesn't factor in to bittering.

Dynachrome said:

Boil without hops the first hour - if I follow - add your hops at 60 minutes remaining. The first hour just reduces your volume and doesn't factor in to bittering.

Click to expand...

Correct but beer smith says it apparently does, so does hopville.

anico4704 said:

Batch sparging, but this I believe applies to both fly and batch. I have read that for higher gravity beers since you have to mash with so much water there is not enough water to fully rinse the grain in the sparge, thus resulting in a much lower efficiency(10-15% lower at least). I am going to do 2 sparges or one giant sparge thus increasing my preboil volume and having to boil longer to get to my OG, hopefully keeping my normal efficiency of 74%. This is a well documented process for large grain bills if you search around google there are far more details than I can provide.

Click to expand...

I get the batch sparge but if you fly sparge it would be one long brew day. Good luck